Unable to use Mosh to connect to one of my servers

I’ve only used Mosh: the mobile shell for a  couple of weeks, but I am definitely a convert! However, I couldn’t get mosh to connect to one of my servers (an OpenVZ instance).

The error manifested itself as the client trying to connect to the server but not getting any response:

mosh: Connecting... [To quit: Ctrl-^ .]

Today I decided to debug the issue. As the client actually was trying to connect, I tried to simply start the server:

$ mosh-server new

MOSH CONNECT 60001 rSbp4ENDdzd/TKBOrrEeVg

mosh-server (mosh 1.2.2)
Copyright 2012 Keith Winstein
License GPLv3+: GNU GPL version 3 or later .
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

[mosh-server detached, pid = 32582]

But when I checked the process list, it wasn’t running anymore:

$ pgrep mosh-server
$

Time to add some verbose output:

$ mosh-server new -v 

MOSH CONNECT 60001 hQ5ab1JjgUytXRZmy5ti6A

mosh-server (mosh 1.2.2)
Copyright 2012 Keith Winstein
License GPLv3+: GNU GPL version 3 or later .
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

[mosh-server detached, pid = 14208]
forkpty: No such file or directory

This must be important: forkpty: No such file or directory, but what does it mean?

Some googling showed that it meant that /dev/pts was not mounted on my system, and it was indeed not mounted:

$ mount
 /dev/simfs on / type reiserfs (rw,usrquota,grpquota)

(Yes, I’ve also wondered why my host is running ReiserFS.)

So I checked my /etc/fsab:

$ cat /etc/fstab
proc  /proc       proc    defaults    0    0
none  /dev/pts    devpts  rw          0    0

It’s there, but still not mounted? Oh well, easy fix:

sudo mount /dev/pts

After that fix, I could successfully connect to my server with mosh!

One thought on “Unable to use Mosh to connect to one of my servers”

  1. Thank you so much! Encountered the same problem, somehow mosh-server only started on root… a verbose check turned out the same problem you described and had to mount /dev/pts

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